DE2352275A1 - Hydraulic circuit arrangement for motor vehicles - has two slide valves each with control chamber to move slides against spring force - Google Patents

Abstract

Hydraulic circuit arrangement esp. for motor vehicles with a pump line and return line for hydraulic fluid passing to and from a container. The control chamber of one valve is continuously connected with a store and is so designed w.r.t. the spring that it carries over, at an upper store pressure, from its first position into a second position in which it connects the control chamber of the other valve with such a first line that its slide interrupts the hydraulic feed from the pump line to the store by connecting the pump line with the return. The slide of one valve in its second position connects the control pressure chamber of the other valve with the store which is then cut off from the pump line.

Description

VOLKSWAGEHWERK Aktiengesellschaft

518 Wolfsburg .
Our reference: K 1593
1702-pt-ha-fi

Hydraulic circuit arrangement for an accumulator charging valve, in particular for motor vehicles

The invention relates to a hydraulic circuit arrangement, in particular for motor vehicles, with a pump line and a return line for a pressure medium tank Pressure medium to be removed and re-supplied, and two forming an accumulator charging valve, respectively a slide containing slide valves, which are used to move the associated slide against the force of a spring from a characterizing the loading phase of the accumulator loading valve first in a second position each have a control pressure chamber, of which the control pressure chamber one of the slide valves is permanently connected to a memory and with regard to the associated slide valve The spring is designed such that it moves out of its first position at a predetermined upper storage pressure in which the control pressure chamber of the other slide valve is not connected to the accumulator, changes to its second position, in which it connects the control pressure chamber of the other slide valve with such a pressure-carrying first line, that its slide the pressure medium supply from dea? Pump line to the storage tank by connecting the pump line to the

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Return line interrupted.

Such an arrangement is already known. In the absence of relevant literature, the state of the art should therefore be discussed at this point with reference to the accompanying drawing. In Figure 1, the circuit arrangement for an accumulator charging valve used in motor vehicle construction is shown, as it corresponds to the type mentioned. The arrangement contains two slide valves 1 and 2 with the associated slide valves 3 and 4 »which, together with the compression springs 5 and 6, are slidably mounted in corresponding housings 7 and 8. The slide valves 1 and 2 are connected to one another via the line system shown and to the memory 3, the pressure medium container 10, the pump 11 and the consumer 12 in connection.

Figure 1 shows the slide position during the loading phase of the storage valve. In it, the pump 11 conveys the pressure medium via the lines 13, 14 and 15 into the memory 9 and at the same time via the line 15 into the consumer line 16. The Lines I7 and 18 are also under pump pressure. Of the Slide 4 is held in the position shown by the spring 6. He closes the muzzle with his piston I9 20 of the return line connected to the container 10 moves when the specified maximum system pressure is reached the slide 3 against the force of the spring 5 upwards. Included the opening 22 of the line 23, which is in communication with the container 10 and is therefore depressurized, is exposed by the piston 24 and at the same time the opening 25 of the line I7 through the Piston 26 closed. The pressure gradient existing between the line 18 or the control pressure chamber 27 and the line 23 is now being dismantled quickly. The pressure in the memory 9 is now sufficient, the slide 4 against the force of the spring 6 so move far down that the opening 20 exposed by the piston 19 and a passage from the line I3 to Line 21 is created. From this moment on, the pump 11 delivers against the pressure in the lines I3 and 21

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Container 10, which will mostly be identical to the ambient pressure. This means that the pump 11, which is directly coupled to the vehicle engine (not shown here) and which runs continuously with it, against the overpressure Hull / Sie accordingly consumes less power, which is of benefit to the engine. A check valve 28 is built into the line I4 so that the accumulator cannot discharge via the line I4.

The consumer 12 can now only be opened directly from the memory 9 ΐ> ^Θ ~, namely via the lines I5 and 16. The pressure in the memory 9 »drops, which means that the spring 5», which is so dimensioned, that it only allows switching of the slide valve 1 at the predetermined upper pressure point of the system, the slide 5 is gradually moved back into the position shown, ie opening is closed and opening 25 is exposed. Despite the now existing connection from the line I7 to the line in this latter and thus in the control pressure chamber 27, no pressure can build up again, which would bring the slide back to its position shown, because the spring is designed so that it is only at the lower Pressure threshold of the system overcomes the accumulator pressure. Until then, the pump is still delivering against the overpressure HuIl. Only when so much energy has been withdrawn from the memory 9 that its pressure has dropped to the predetermined lower pressure threshold does the slide 4 move back into its position shown. This is initially done solely by the force of the spring 6. However, as soon as the opening 20 is only slightly covered by the piston I9, a throttling effect occurs in this area, with the result that a pressure builds up immediately in the line 13, which propagates via the lines I7 and 18 to the control pressure chamber 27 and there, the action of the spring 6 increases, so the movement of the slider 4 i ⁿ its drawn position accelerated. This means that the return

5098 1 7/01 72 "

line 21 closed again, and the pump delivers "up to When the upper pressure threshold is reached again in the memory 9

This known arrangement has the disadvantage that the return line 21 is not resilient. If you were to switch on a consumer in this return line 21 that would anyway could only be operated outside of the charging phase, but this would be sufficient in certain cases in the lines I5, 17 u ^ -d 18 build up sin pressure, which the Slide valve 2 could be switched over prematurely. i.e. before the memory 9 ^ is emptied to the lower pressure threshold. In order to the consumer in the return line 21 would also quickly switch itself off again »

The object of the invention is therefore to improve the known circuit arrangement so that a load the return line has an effect on the storage circuit remain. According to the invention, this object is achieved in that the slide of one slide valve is in its second position connecting the control pressure chamber of the other slide valve to the accumulator, which is then separated from the pump line is executed.

In this way it is possible to combine a hydraulic arrangement working in storage mode with consumers working in flow mode. A decisive advantage of the invention lies in the fact that one needs despite dev two different modes of operation, the storage operation and the flow-through operation, only one pump. In addition, the expenses for the line structure in the arrangement according to the invention are significantly lower than in two separate circuits, because the return line, which is also used in flow mode, is already present in the arrangement in storage mode.

ORlQlNAL inspected 509817/0172

A "preferred embodiment of the invention is thereby characterized in that the pressure prevailing in the pump line during the loading phase of the accumulator loading valve via the Another slide valve designed as a three-two-way slide valve acts on the one hand on the memory and on the other hand via two further lines on the one slide valve, wherein one of these lines opens into the control pressure chamber of a slide valve and against an end face control surface one of two pistons of the first slide is directed, while the other line is directed at the circumference of the one slide valve opens into an opening which, depending on the prevailing pressure conditions, is covered by the other piston or in the distance between the two pistons via the first line a connection of the pump line to the Manufactures control pressure chamber of the other slide valve.

To manufacturing tolerances in the dimensions of the slides and To compensate for their housing, it is advantageous that the spaces in the slide valves, each on that of the control pressure chamber facing away from the slide, connected directly to the pressure medium tank via leakage lines are. This prevents leaks between the pistons and their housings in them Evacuation builds up a pressure that the switching function of the slide valves would adversely affect. In order to further increase the operational reliability of the circuit arrangement it is appropriate that the one slide valve on its circumference one with the pressure medium tank in direct connection has standing further opening, which corresponds to the respective pressure conditions through that of the control pressure chamber adjacent one piston of the first slide belonging to a slide valve is sealed or free in the Distance between the two pistons. This allows the first line, which connects the two slide valves to one another be depressurized before the other Shie-

-ORlGlNAL INSPECTED 5098 17/0 172

berventil associated second slide from its second position, in which it is when the upper pressure threshold of the system is reached moved back to its first position. This helps ensure that the top and bottom are each given Switching point can be adhered to more precisely.

According to a further embodiment of the invention, compliance with the upper and lower switching points can thereby be increased be that between the two slide valves existing first line via a first throttle line the space in the other slide valve communicates with that of the control pressure chamber of the other slide valve opposite side of the associated slide is located. To the same The purpose can be a further throttle line between the memory and the control pressure chamber of the other slide valve to be on.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Show it

FIG. 1 shows a circuit arrangement which belongs to the prior art and has already been described in more detail above of the type mentioned at the beginning and

3? Figure 2 shows a preferred embodiment of the circuit arrangement according to the invention.

The circuit arrangement shown in FIG. 2 initially comprises two slide valves connected to one another by lines and 102, each consisting of the housings 103 and 104 and the slides 105 and 106 slidably mounted therein. The slides 105 and 106 each consist of two piston rods 107 and 108 interconnected pistons 109 and 110 or 111 and 112. The pistons 110 and 112 are supported Via compression springs 11J and II4 each against an end face

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the housing 103 iuia IO4. To the left of pistons I09 and 111 are located within the slide valves control pressure chambers 115 and 116, which are in the position of the slide shown just completely filled by pistons I09 and 111 are.

The gate valve 102 is a three-two-way gate valve. It is connected to the pressure side of the pump 118 via the line 117 »^ i ^{e pump line.} Furthermore, the line 120 leading to the accumulator II9, the accumulator line, and the return line 122 leading into the pressure medium container 121 are connected to the slide valve 102. A line 123 branches off from the accumulator line 120, via which a first consumer 124 ¹ ^ "t accumulator pressure is applied and which then opens into the return line 122. Via a line 125, the accumulator-pressurized line 120 with the control pressure chamber 115 is in the slide valve 101. Between the two pistons I09 and 110 there is a connection in the housing 103 for the line 126, which opens into the control pressure chamber Ho of the slide valve 102. A line 127 branches off from the line 125, the opening of which in the housing I03 depending on the position of the slide 105 is closed by the piston 110 or is exposed in the distance between the pistons IO9 and 110 and then establishes a connection between the line 125 and the line 126.

The drawn position of the slide 105 and I06 gives the Loading phase of the accumulator loading valve again. In this state, the pump 118 conveys this from the pressure medium container pressure medium sucked in via line II7 through & s slide valve 102 through and via the line 120 into the accumulator 119. The accumulator pressure also prevails in the line 123 and there it can hit the possibly connected consumer 124 ^ ea. The accumulator pressure that builds up also propagates via line 125 into control pressure chamber 115.

5098 17/0 172 ORIGINAL INSPECTED

As soon as the force exerted on the piston 109 resulting from the accumulator pressure is greater than the force of the spring 113, the slide 105 gradually moves to the right, until the piston 110 releases the mouth of the line 127, at the same time the piston 109, the opening 128 of the with completes the line connected to the pressure medium tank. The line 127 "is now also being built Storage pressure in the line 126 and moves, provided the predetermined maximum storage pressure is reached, the slide 106 from its illustrated left end position against the force of the spring 114 to the right. So the spring II4 is designed so that until shortly before reaching the selected upper pressure point, the slide IO6 is in its left end position is able to hold while the spring II3 in the Schiefer valve 101 corresponds to the lower pressure point of the system. When the slide I06 moves into its right end position, the piston 111 closes the access to the line 120, while the piston 112 closes the opening to Line 122 releases. The pump 118 now delivers directly into the return line, while the consumer 124 is now operated only with the energy supply in the memory 119 can be. A particular advantage of this circuit arrangement is that the return line can be subjected to pressure, without this pressure being in propagates the storage circuit and thereby has repercussions on the switching function. So can in the return line another consumer I30 can be switched on, the outside the charging phase is applied directly by the pump. The consumer 1JO is opposite the consumer 124 of of minor importance. For example, the circuit arrangement according to the invention can be installed in a motor vehicle The pump is driven directly by the vehicle engine, i.e. as soon as the engine is running, the pump also runs. Functions that are important for road safety, such as applying the brakes or steering, are supported with the help of

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the energy available in the memory executed; Less important functions, such as level control or the operation of a sliding roof or a crank window, can be carried out outside the loading phase with the aid of a servo motor (consumer 150) connected to the return line 122 in flow mode. Such subordinate functions are already often carried out in flow mode, because the effort for this is significantly less than in storage mode. Nevertheless, a separate pump has always been required for this up to now. Because of the invention, this is no longer necessary. Whilst there is a storage system in the vehicle anyway, consumers can now also be coupled to it in flow mode, so that you can always get by with a single pump.

About possible manufacturing difficulties during manufacture of the slide valves with respect to the required tolerances between the piston and the housings will be encountered further measures are proposed to ensure proper operation of the accumulator charging valve. It will hardly be like that be avoidable that during the charging phase between the piston 112 and the surrounding wall of the housing I04 a part of the pressure medium in the receiving the spring II4 Tree 131 arrives. Here would be a time to buy also build up low pressure, which would be large enough, however, the exact Umsehaltfunktion the slide 106 to the predetermined Adversely affecting pressure points. The same applies to the seam 1J2 in the slide valve 101. For this reason are the rooms 1J1 and 132 with leakage lines 133 and 134 connected, which ultimately open into the pressureless pressure medium container and thus a harmful pressure build-up in the chambers 131 and 132 do not even arise.

As another precaution in terms of optimal The auxiliary control lines 135 and I36 are operational safety

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ORIGINAL INSPECTED

with don. built-in chokes 157 ^ ¹¹ ^ 158.

The mode of operation of these auxiliary control lines is as follows;

During the loading phase, the slide 105 is gradually moved to the right, in the process - possibly due to production - the opening 128 of the line 129 is covered by the piston 109 before the opening of the line 127 is released by the piston 110. Possible leaks at the piston 110 can cause a pressure to build up in the slide valve 101 between the pistons 109 "^ cL 110, which would move the slide 106 to the right prematurely, ie before the intended upper switching point (eg 180 bar) is reached. In order to reduce this premature pressure in the line 126, it is connected to the tank line 153 via the throttle line 135 Kit, which, as already mentioned, is depressurized or, to put it more precisely, in which no overpressure can build up the opening of the line 127 through, the piston 110 is released, the throttle 157 virtually prevents the required switching pressure in the control pressure chamber 116 from occurring, because the pressure medium cannot escape so quickly via the line 135 precisely because of the throttle 137.

Once the specified upper pressure threshold has been reached the two sliders I05 and I06 on your right End position. As the accumulator pressure decreases, the slide 105 moves to the left again. By 3? Erti # intolerance in piston I09 it could be that via line 129 a pressure drop arises in the slide valve 101 which increases would also extend to the line 126 and would result in the slide I06 going to the left of the compartment prematurely. The slide I06 should only switch over at a defined lower pressure threshold. That is why the line becomes 12β Leaking pressure from the accumulator via throttle I38

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replaced. When the line 129 is fully opened, the throttle 138 ensures that the memory 119 does not pass through the line 129 is emptied.

ORiGlNAL INSPECTED 5098 17/0 1 7 2

Claims (6)

AHfSPRTTCHE '1. ) Hydraulic circuit arrangement, in particular for motor vehicles, with a pump line and a return line for a pressure medium to be removed from a pressure medium container and to be supplied again, and two slide valves forming a storage loading valve, each containing a slide, which are used to move the associated slide against the force of a spring from a first characterizing the loading phase of the accumulator loading valve to a second position each have a control pressure chamber, of which the control pressure chamber of one of the slide valves is permanently connected to a memory and is designed with regard to the associated slide spring such that it is at a predetermined upper level Storage pressure from its first position, in which the control pressure chamber of the other slide valve is not connected to the memory, passes into its second position, in which it controls the control pressure chamber of the other slide valve with such a pressure Recirculating first line connects that its slide interrupts the pressure medium supply from the pump line to the accumulator by connecting the pump line to the return line, characterized in that the slide (IO5) of one slide valve (101) in its second position the control pressure chamber (116) of the other Slide valve (102) is designed to connect to the storage (II9), which is then separated from the pump line (117-). 509817/0 172 2. "Circuit arrangement according to claim 1, characterized in that the pressure prevailing in the pump line (117) during the loading phase of the accumulator charging valve via the other slide valve (102) designed as a three-two-way slide valve on the one hand on the memory (119) and on the other hand, via two further lines (125, 127) on which one slide valve (101) acts, one (125) of these lines opening into the control pressure chamber (115) of one slide valve (ΙΟΙ) and one (I09) of two against an end control surface Piston (109,110) of the first slide (I05) is directed, while the other line (127) on the circumference of one slide valve (ΙΟΙ) opens into an opening (139) which, depending on the prevailing pressure conditions, of the other piston (IIO) is covered or at the distance between the two pistons (I09, HO) via the first line (126) a connection between the pump line (II7) and the control pressure chamber (II6) of the other slide valve (102 ) manufactures. 3 circuit arrangement according to claim 2, characterized in that that the spaces (131> 132) in the slide valves (102, 101), which are located on the side of the slide (ΙΟβ, IO5) facing away from the control pressure chamber (II6, 115) Leak lines (133 »134) are connected directly to the pressure medium tank (121). 4. Circuit arrangement according to claim 2 or 3> characterized in that that the one slide valve (ΙΟΙ) on its circumference has a further opening (128) which is in direct communication with the pressure medium container (121) and which according to the respective pressure conditions through the one piston (I09) adjacent to the control pressure chamber (II5) of the first slide (I05) is sealed or lies freely in the distance between the two pistons (109, HO). 509817 / 0-172 ' 5. Circuit arrangement according to claim 4 »characterized in that the valves between the two Schiä> erventilen (101,
102) existing first line (126) via a first throttle line (135) niit the space (I3I) in the other slide valve (102) in connection, which is on the
Control pressure chamber (116) of the other slide valve (102) facing away from the associated slide (I06). 6. Circuit arrangement according to claim 4 or 5> characterized in that between the memory (119) and the
Control pressure chamber (116) of the other slide valve (102) another throttle line (I36) is switched on. 509817/0172 Blank page